1. Technical Field
The present invention relates to a polypropylene resin composition with superior rigidity, scratch resistance and glossiness, laser processability, low temperature impact resistance and fluidity suitable for interior materials of a vehicle, including an air bag deployable instrument panel.
2. Background Art
Being superior in molding property, impact resistance, chemical resistance, specific gravity and cost, polypropylene composite resins have been widely used for manufacturing interior and exterior materials of vehicles. Especially, they are suitable to be used in parts where safety and functionality are of significance, for example, as an instrument panel. However, although the polypropylene resin compositions developed thus far are superior in physical properties such as rigidity, scratch resistance, impact resistance, etc., the fluidity tends to decrease reversely proportional to the physical properties. As a result, it is still difficult to use them to manufacture thin, lightweight parts, and also problems such as poor surface appearance or scratches may occur. And, if the fluidity of the resin is increased, the impact resistance decreases and there is a possibility of breaking into pieces when an accident occurs. Besides, the decreased rigidity of the molded part makes the assembly with other parts difficult due to deformation and warpage.
Several types of polypropylene-based resin compositions for interior materials of a vehicle have been developed. For example, Korean Patent No. 10-0263332 discloses a resin composition having superior physical properties including rigidity and/or capable of being directly coated with paint without primer treatment. Korean Patent No. 10-0412452 discloses a resin composition for an air bag deployable instrument panel which can be directly coated with paint without primer treatment. Korean Patent Application No. 2005-72514 discloses a polypropylene resin composition for interior materials of a vehicle having improved scratch resistance and molding property. However, since impact resistance, scratch resistance, impact resistance or rigidity are contradictory to fluidity property, there has been no resin composition suitable for an instrument panel which is required to meet both properties.
For example, although the resin composition for an air bag deployable instrument panel (Korean Patent No. 10-0412452) provides excellent rigidity and coatability and has superior low-temperature impact resistance required for the inflating of the air bag, it has appearance problems such as weld line, sink, flow mark, etc. due to low fluidity and requires coating due to insufficient scratch resistance.
Accordingly, there is a need for the development of a polypropylene resin composition having physical properties enough to eliminate the coating process for cost reduction, as well as high fluidity, superior scratch resistance, and low-temperature impact resistance required for the inflating of the air bag.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.